The present invention relates to a method and apparatus for testing optical systems. More particularly, this invention relates to a method and apparatus for checking and measuring optical data of optical assemblies for endoscopes. Specifically, this invention relates to a method and apparatus for testing endoscopes of different physical and optical configurations.
Endoscopic image transmitting optical systems are extensively used to permit visualization of typically inaccessible areas within a patient""s body. These systems generally include a housing enclosing a lens portion for focusing and relaying an image, and an illumination means for illuminating the region to be viewed. In endoscopic surgical procedures, relatively narrow surgical instruments are inserted into the patient""s body so that the distal (i.e., working) ends of the instruments are positioned at a remote interior site, while the proximal (i.e., handle) ends of the instruments remain outside the patient""s body. The surgeon then manipulates the proximal handle ends of the instruments as required so as to cause the distal working ends of the instruments to carry out the desired surgical procedure at the remote interior site.
The endoscope generally comprises an elongated shaft having a distal end and a proximal end, and at least one internal passageway extending between the distal end and the proximal end. An image capturing device is disposed at the distal end of the shaft and extends through the shaft""s internal passageway to capture an image of a selected region located substantially adjacent to the distal end of the shaft and convey that image to the proximal end of the shaft. A viewing device is in turn disposed adjacent to the proximal end of the shaft, whereby the image obtained by the image capturing device can be conveyed to a display device which is viewed by the surgeon.
With this arrangement, the viewing device can comprise a display device in the form of a conventional optical viewer or eyepiece which is viewed directly by the surgeon. Alternatively, the viewing device can comprise an appropriate image sensor, e.g. a charge coupled device (xe2x80x9cCCDxe2x80x9d) element, which receives the captured image from the proximal end of the fiber optic bundle and generate corresponding video signals which are representative of the captured image. These video signals are then displayed on an appropriate display device (e.g. a monitor) which is viewed by the surgeon.
Quality of an image transmitted by a typical endoscope critically depends on its optical performance and needs to be tested before the endoscope is used in a surgical procedure. Both a lens system and a fiber optic illumination system of an endoscopic assembly should be carefully evaluated. Thus, for instance, damaged fiber wires can be responsible for only partially transmitted light. A damaged lens system leads to a distorted image or to blurring the sharpness of image colors. To avoid these and other drawbacks in the optical performance of endoscopes as a result of the manufacturing process it is known to use diagnostic systems.
U.S. Pat. No. 4,613,232 to Diener et al. discloses a measuring device for testing optical systems of an endoscope which includes a linearly displaceable guide rail receiving a shaft of an endoscope. To evaluate different optical and physical characteristics of a tested endoscope, this reference discloses different targets, each for performing a respective test and mounted on a separate displaceable arm.
Having differently dimensioned arms may lead to complicated kinematics of the testing system because each given test has be conducted in a precise position of the respective arm with respect to the tested endoscope. To computerize such complicated system may be very difficult since every arm would need its separate access motion.
U.S. Pat. No. 5,841,525 to Rosow discloses a testing system including a linearly displaceable carrier which supports a set of different targets, each selectively aligned with a tip of an endoscope for conducting a given test. An endoscope is mounted on an angularly displaceable arm.
In order to perform different tests, the carrier must be removed, rotated at a 180xc2x0 angle and repositioned in a respective alignment position, which makes computerization of this system difficult to achieve. Further, an endoscope is mounted on an upright rotatable arm whose displacement requires a lot of space that may be rather scarce at a location where an endoscope is being tested. Still another disadvantage of the system disclosed in this reference is that a single fiber optic cable is used to perform a transmission measurement of the illumination fibers. Thus, first a user measures the output of a light guide, then reattaches it to an endoscope to measure its output. The ratio of the outputs is the transmission of the endoscope. This, however, involves the user taking a measurement before and after the light guide is attached to the endoscope making the test unnecessarily complicated.
What is desired, therefore, is a testing system having a single support mechanism that can automatically perform all necessary displacements of targets adapted to conduct a variety of tests without a need to manually replace and reposition different parts. Further, a testing system for automatically evaluating and displaying the results of a variety of tests based on comparison of the performance of an endoscope to be tested with the performance of a standard endoscope is also desirable, as is a testing system for automatically conducting a series of tests on an endoscope in response to a variety of parameters introduced by a user.
A device and method for testing a variety of endoscopes in accordance with this invention address many of the above-discussed problems of the known prior art.
Particularly, a device for evaluating optical performance of endoscopes provides a variety of tests by provision of a testing station which is rotatably and linearly displaceable relative to a fixed position of a distal end of a tested endoscope.
The testing station includes a turntable rotatable about a first axis and supporting a linearly movable carousel support which, in turn, rotatably supports a carousel of targets to measure the optical performance of an endoscope.
The tests to be performed on both a flexible endoscope and a rigid, rod lens endoscope may include evaluation of field of view, angle of view, distortion, depth of field, of illumination system transmission efficiency, illumination profile, and relative transmission of imaging system and of centering error. The only difference between the flexible and rigid types is that an image quality test can be performed only on the rigid scope. It is possible to use four targets including a grid of pinholes, a diffuse but translucent white target, a single pinhole target and a luminous flux detector that should be sufficient to make all of the required measurements.
The device according to the invention is capable of testing a Karl Storz endoscope by comparing its performance with a standard scope of the same type stored in the database. Further, the device is capable of examination of any endoscope by comparing its performance with a standard Karl Storz endoscope whose characteristics stored in a database and are comparable with the characteristics of the endoscope to be tested. Alternatively, the device can test an endoscope without comparing it to a standard one and, afterwards, add a set of parameters of this new type of the endoscope to the system""s database.
According to another aspect of the invention, the system has a support station adapted to receive a CCD camera which, in turn, receives an eyepiece of an endoscope to provide vertical and angular adjustment of the latter with respect to an alignment target. The support station is controllably displaceable along a horizontal rail to displace a distal end of the endoscope toward and away from the testing station.
In accordance with another aspect of the invention, the horizontal rail is mounted on a riser block which can be controllably actuated to move the support station at a predetermined vertical distance. Mounted on an opposite end of the rail is a xe2x80x9cVxe2x80x9d block assembly adapted to provide a correct horizontal position of the endoscope. The V block assembly has an adjustable arm formed with a V shape groove which receives a shaft of the endoscope as the block slides along the rail.
The support station in combination with the xe2x80x9cVxe2x80x9d block assembly allows the endoscope to be properly aligned with respect to an alignment target specifically designed to position the endoscope in a predetermined aligned position with respect to the testing station. As is known, proper alignment of an endoscope is critical. Misalignment of the endoscope can lead directly to inaccurate test data. Upon establishing the proper horizontal position, the support station is controllably displaceable to enable vertical and horizontal edges of a slit formed in the alignment target to be centered in the field of view of the tested endoscope.
An automatic process is completed by controllably rotating the carousel at predetermined angles so that each of the targets is aligned with the distal end of the scope. In accordance with the invention, each of the tests is processed and the results are displayed on a monitor.
It is therefore an object of this invention to provide a device for automatically evaluating the optical performance of an endoscope.
It is another object of the invention to provide a device for automatically evaluating the optical performance of endoscopes having varying physical characteristics.
It is still another object of the invention to provide a device for automatically evaluating the optical performance of an endoscope which has a variety of targets controllably rotatable relative to the tested endoscope to predetermined angular positions.
Still another object of the invention is to provide a device for automatically evaluating the optical performance of an endoscope which has a turntable for automatically adjusting a nominal angle of view of a tested endoscope.
It is a further object of this invention to provide a device for automatically evaluating an optical performance of an endoscope which has a linearly displaceable carousel support to provide a safe alignment of an endoscope and a predetermined distance between each of the targets and the endoscope.
Still a further object of the invention is to provide a device and method for operating this device allowing a user to perform a series of selected tests evaluating an optical performance of an endoscope.